Magnetic template-follower



Dec. 24, 1935. 1 ANDERSQN 2,025,081

'MAGNETIC TEMPLATE FoLLowER FilBd June 26, 1954 INVENTOR MAM BY j

ATTORNEY Patented Dec. 224, 1935 PATENT OFFICE 2,025,081 MAGNETIC TEMPLATE-FOLLOWER James L; Anderson, Closter, N. J., assignor to Air Reduction Company, N. Y., a corporation o Incorporated, New York, i' New York Application June 26, 1934, Serial No. 732,478

13 Claims. (Cl. 33-23) This invention relates to magnetic templatefollowers for moving a cutting or welding torch, or other instrumentality, in accordance with the -outline of a template.

A In the known types of magnetic template-followers the roller isrotated by a constant speed motor, and is magnetized, to cause'it to adhere to the template, by a solenoid located immediatesupported for universal movement in a plane and is connected with a torch-holder by connections which cause the torch to follow a path similar to that traveled by the template-follower.

Asthe motor rotates the roller at uniform speed, friction between the roller and template causes the roller to travel along the side surface of the template with uniform lineal speed and the torch is moved along a similar path at uniform speed. y

In order to make smooth and accurate cuts it is necessary to maintain a uniform torch speed. Slipping of the rollerl on the template because of insuiiicient friction can not be tolerated. The

roller of the template-follower is usually knurled so that it will not slip easily, but it is also necessary to maintain a strong magnetic attraction in order to insure suiicient friction.

Besides the risk of variation in torch speed, a

follower with weak magnetic attraction between the roller and template is likely to be jarred away from the template,l so that the torch swings out of the desired path and ruins the work.

Electromagnets using direct current are the only means with which the prior art has succeeded in obtaining suiiciently strong magnetic attraction to insure Asatisfactory operation of magnetic template-followers. In many locations alternating current is the only commercially available power and in such cases the provision of motor-generator sets or other sources of direct current has been an inconvenience and expense incident to the use of magnetic templatefollowers.

5 It is an object of this invention to provide an improved magnetic template-follower in which the magnetic flux from a plurality of magnets is concentrated in the roller to strongly mag- D netize the roller. This feature of the invention makes it possible to obtain a strong magnetic attraction between the roller and a template, even though the individual magnets are of much less strength than the lelectromagnets of the prior i art. With this invention the necessary magnetism for the roller can be obtained from alternating current or permanent magnets.

Another object of the invention is to provide a magnetic template-follower which requires no electric power to magnetize the roller, but ob- 5 tains a strong magnetism for the roller from one or more permanent magnets constructed and combined with the roller in a novel manner.

Other objects, features and advantages of the invention will appear or be pointed out as the 10 specification proceeds.

In the accompanying drawing, forming part hereof:

Fig. 1 is a perspective view of a universal cutting machine with a template-follower embodying 15 the invention;

Fig. 2 is an enlarged vertical sectional view through the template-follower shown in Fig. 1;

Fig. 3 is a top plan view of the template-follower shown in Fig. 2 with the cover removed; and 20 Figs. 4 and 5 are views corresponding to Figs.

2 and 3, but showing a modified form of the invention.

Magnetic template-followers are used on different types of universal cutting machines and 25 the jointed arm machine shown in Fig. 1 is mere-- ly illustrative of a universal torch machine ln which a magnetic template-follower moves a torch along a path similar to the outline of a template. 30

The universal cutting machine shown in Fig.

1 is of the type in which the template-follower is in vertical alinement with the torch. A jointed arm I 0 is supported by a post II for swinging Y. movement in a horizontal plane. The post I I rises 35 from a base I2. A template I4 is supported at the top of the post II by a clamp I5 on the post.

A pivot connection I6 comprises the joint of the jointed arm.

A torch-holder II at the free end of the forward link of the jointed arm I0 supports a torch I8 which can be moved toward and from the work by a hand-wheel I9 operating rack and pinion mechanism which is well understood in the art.

A template-follower 2| is connected to the 45 forward link of the jointed arm by a bracket 22 and is located in such position that the axis of the template-follower roller 23 is in line with the center of the cutting jet of the torch. 'I'he template-follower 2| is operated by a motor 25 50 which is of the governor-controlled type commonly used for template-followers, with a knob 26 for adjusting the governor to change the motor speed.

Fig. 2 shows the roller 23 integral with a col- 55 flat outside faces of a hub or sleeve I0 threads into a'central 'recess in lthe bottom-face of the collector' 28.-'and th magnets 29' are fastened to the sleeve Il by screws 3i. The sleeve lil can be made with for contact with the-sidesof the magnets, but this is the screws 8l hold the vmagnets in radial posi"- tions when clampingthem outside wall of the sleeve 88.

In the embodiment of the invention illustratedl the magnets 29 are permanent magnets and are I2' and a cover I8. This enclosed by a casing cover is preferably made of amyl acetate, or other non-magnetic material, and it has a central opening through which the roller 2l extends.

The outer poles onthe magnets 28 are longer than the inner poles and extend close to the level 'of the template I4. There are a sufficient number of magnets 29 .evenly spaced around the rollerl 23 so that two or more of the outer poles are always under the template when the follower is in operation. The magnetic circuit extends from the inner poles of the magnets 28 through the collector 28 which concentrates the ux from the magnets into the roller 23 from which it passes through the template and then acrossthe short air gap between the template and the outer poles -of the magnets 28 below the template.

There is a flange 35 near the lower end of the sleeve 80,.and the casing 32 is connected with the sleeve by screws 36 extending through the bottom of the casing and threading into the flange. 35. Thus, the roller 23, collector 28, magnets 29, sleeve 38, and casing 32 are connected together tc rotate as a unit, and they are supported on a hollow post 38 as abearing, with an anti-friction thrust bearing 88, at the upper end of the post, supporting the weight of the rotating structure.

A drive shaft 4I extends through the hollow post 38 and collector 28. The hollow post I8 connects, at its lower end, with a cover plate 43 of a gear housing 44 carried at the outer end of the bracket 22. The lower end of the drive shaft 4i extends through a ball-bearing 45 which fits into a recess in the bottom face of the cover plate 48. A nut 48 is threaded on the lower end of the drive shaft and abuts against the inner race of the ball-bearing 45. This nut prevents the drive shaft from being lifted out of the hollow post and thus holds the rotating portion of the tracing device in assembled relation with the non-rotary portion.

A worm-wheel 48 is secured to a shaft 48 which turns in a central boss 60 as a bearing, and is operatively connected with theroller drive shaft 4I by a tongue and groove coupling. There is a ball-bearing thrust washer 52 between the worm-wheel 48 and the boss 50.

The worm-wheel 48 is driven by a worm 53 on a shaft 54 journaled in bearing lugs Il on the inside wall of the gear housing. One end of the shaft 54 extends beyond the gear housing 44, and through a shaft housing l1 to the reduction gearing at the end of the armature shaft of the motor 25. Such reduction gear drives are well known on motors of the type used for template-followers and its illustration therefore unnecessary.

Figs. 4 and 5 show a modified form of the l f @osmosi l magnets 2t.

not necessary because against a cylindrical plate.

bearing 38, and threads into thel invention in which. an annular permanent malnet 8l, vhaving a radial cross-section of horseshoe form, is employed inplace of the ring of The radial thickness .ofthe outer pole is preferably lessthan that of the inner 5 pole so that the areas of the pole vfaces are substantially equal vin spite of their differences in circumference.

In Fig. 4 the magnet 80 is fastened to the bottom of the casing, by screws 82 instead of being fastened to the sleeve I0 as in Fig. 42.4 This difference is necessary because the annular forml of the magnet makes it dlillcult to drill radial 4holes through the inner pole. 'The hollow shaft y in Fig. 4,'since the structure enclosed is identical with that illustrated in Fig. 2.

Although thetemplate-follower of this invention has been described with particular reference to the moving of a cutting torch, it will be 20 understood` that the -invention can be used for operating various devices which it is desirable to move in accordance with the outline of a tem- It will be apparent that this templatefollower is not limited to the particular embodi- 25 ments which have been illustrated and described and that features of the invention may be used without others.

I claim:

1. A follower for template-controlled appara- 30 tus including a roller for contact with the tempiate, and means for magnetizing the roller vto cause it to adhere to the template including at least one magnet and a tapered ilux collector over one pole face of the magnety and 'in position to 35 concentrate in the roller the ux from said pole face.

2. A follower fo'r template-controlled apparatus including a roller for contact with the template, and means for magnetizing the roller to l( cause it to adhere to the template including a plurality of magnets at spaced points around the roller, a collector in the magnetic circuit with the roller, said collector extending close to the oorresponding pole faces of the magnets and decreas- ,Il ing in size toward the rollerso that it Aserves to concentrate the magnetic ux in said roller.

3. A magnetic template-follower comprising a roher for contact with the template, a truncated# conical collector immediately below the roller 6 and coaxial with said roher, driving mechanism including a shaft extending downI from the roller and collector, an annular, horseshoe-type magnet surrounding the shaft, and'having one of its annular pole faces immediately below the col- I lector so that the collector concentrates the ux from that pole face in the roller.

4. A magnetic template-follower comprising a roller, means for magnetizing the roller including one or more magnets with corresponding palet faces in position to magnetize the roller, and having one or more pole faces in a plane higher than the mst-mentioned pole facesfor completing a magnetic circuit through the template when the roller is in contact with a template, a collector for concentrating the magnetic flux in said roller to cause the roller to adhere strongly to the template and mechanism for rotating the roller to cause it to travel along the edge of the template.

5. In a template-follower of the type having a roller which travels along the edge of a template and is held in contact with the template by magnetic attraction, a hub, a plurality of magnets held against the hub and located around the hub I with their corresponding pole faces close to the roller so that their combined magnetism is available to magnetize vthe roller.

6. In template-follower apparatus of the type having a roller which travels along the edge of a template and is held in contact with the template by magnetic attraction, a number of corresponding magnet poles around the roller, and means supporting said magnet poles close to the roller so that the roller receives ilux from all oi' said magnet poles.

7. A template-follower comprising a roller, a plurality of horseshoe-type magnets located around the roller and having poles of different lengths, the short pole of each magnet being in position to magnetize the roller and cause it to adhere yto a template, the longer poles of the magnets terminating in a plane which is close to the template when the roller is in contact with a template, and driving mechanism for rotating the roller to cause it to travel along the template.

8. In template-controlled apparatus, the combination of a roller, a plurality of corresponding magnet poles around the roller, means supporting the magnet poles in such positions that they all combine to magnetize the roller, and driving mechanism connected with the roller and the pole supporting means for rotating the roller and magnet poles as a unit.

9. A template-follower comprising a roller and plurality of magnets with a collector in position to concentrate ilux from all of the magnets in the roller, means connecting the roller, magnets, and collector so that they turn as a unit, and driving mechanism for rotating the roller, magnets, and collector.

10. Ina template-follower of the type having a roller which travels along the edge oi' a template and is held in contact with the template by magnetic attraction, means for rotating the roller including a drive shaft, an annular mag-l net, oi channel cross-section, surrounding the drive shaft with the inner pole face of said annular magnet in position to magnetize the roller, 5 and the outer pole i'ace in position to extend under the template when any point on the circumference of the roller is in contact with the template.

11. Apparatus oi.' the character described including a roller for contact with a template, mechanism for rotating the roller to cause it to travel along the template, an annular magnet around the roller with the inner pole face in position to magnetize the roller, and means connecting said annular magnet with said mechanism so that the roller and magnet rotate as a unit.

12. A template-follower comprising a roller, mechanism for rotating the roller including a drive shaft coaxial with said roller, an annular magnet of channel cross-section along its radius, zo the inner pole face o! the magnet being of substantially larger extent than a section through the roller parallel to said face, and a collector between the roller and magnet, extending over said inner pole face ci the magnet and tapering toward said roller to provide a magnetic circuit between the Amagnet and roller, and to concentrate in the roller the ilux from said pole face.

13. A magnetic template-follower comprising a power-driven roller for contact with a template, and magnetic means for holding the roller against the template including a plurality of magnets and a collector in position to concentrate the ilux l from said magnets and produce a iield intensity, adjacent the edge or the template, greater than that oi' the individual magnets.

JAMES L. ANDERSON. 

